1. Technical Field of the Invention
The present invention relates to a helmet restraint system for restraining the forward and downward movement of an occupant's helmet and head, in particular adapted for a heavy pilot helmet having an unfavorable centre of gravity, comprising a buckle strap having a first end and a second end, first attachment means engaged with said helmet and adapted for being associated with said buckle strap and second attachment means engaged with the buckle strap. More particularly, the invention relates to a system for operationally securing a helmet worn by a driver, pilot or occupant of a high-performance vehicle such as a race car, aircraft or boat, to the garment of e.g. said pilot.
Problem
Recently, in aircrafts and helicopters the use has increased of helmet mounted systems like Helmet Mounted Display (HMD), pilot helmets provided with Night Vision Goggles (NVG's) and heavy pilot helmets having an unfavorable/adverse centre of gravity. Therefore, helmets provided with HMD and NVG induce an increase in load forces to the muscles, tissues and ligaments of the pilots head and neck. It is well known that even helmets with a relatively well-arranged centre of gravity might cause neck injuries in conditions involving a heavy G-load combined with continuous use. It is expected that an adverse centre of gravity will result in an increasingly higher chance for neck injuries. Further, the specific design of a helmet in combination with the pilot's body-position, heavy G-load and -acceleration during flight and long lasting flights, would cause heavy load forces to the muscles and tissues of the pilots head and neck. In the HMD- and NVG-cases the center of gravity is located far forward and high up (forward high) in relation to an optimum centre of gravity. This will result in a high moment factor to the neck during flight, which must be compensated by neck muscle activity. A heavy weight combined with an adverse centre of gravity will also result in a high inertia moment which in turn might cause unpleasant rotational movements to the neck together with increased shearing strain in the spinal column. These elements all together would result in increased strain to muscles, spondyls, tissues and ligaments.
Observations related to complex neck problems of fighter pilots include among others fatigue of muscles and degenerative changes. Fatigue might result in decreased efficiency to the pilot with shortened flights and would most likely be aggravated by an unfavorable helmet design. Helmet mounted systems also increase the static load on the neck. It has been observed that static load during e.g. transport flights might accelerate the degenerative changes and it is believed that this phenomenon would be enlarged by an increase in weight and by an adverse centre of gravity. Information taken, degenerative changes might result in a chronic injury by elderly people meaning dehydration and crack formation of the vertebrae. Hence, it has been observed that fighter pilots get degenerative changes prematurely as a result of a continuous exposure to high G-loads.
2. Description of Related Art
Conventionally, for example NVG's are used in combination with counter weights in order to improve the centre of gravity location and enlarge the pilot's comfort. However, these measures are not optimal as, on the one hand, the back space is limited but firstly because of the unwillingness to add to the inertia factor. A rise in the inertia moment would cause enlarged rotational movements of the pilots head during maneuvers involving steep turns and/or aerobatics, which would result in unpleasant moment factors to the neck and increased muscle activity. Therefore, usually no external support is used to relieve the pressure on the pilot's neck, for example in jet fighters.
GB 564614 discloses a safety device for e.g. for pilots, intended to prevent dislocation of the neck on a sudden stop. Said safety device comprises an elongated frame secured to the pilot's back and having a rigid projection secured to the helmet by a strap of such length and elasticity as to prevent injurious forward jerk of the head. The frame may be incorporated in the pack of the parachute.
U.S. Pat. No. B1-6,810,535 discloses a helmet restraint device of the initially defined kind, which reduces potentially injurious forces to the occupant's head and neck during high-deceleration of a vehicle, particularly a frontal collision. A rod is disposed behind and below the occupant's neck, just beneath the shoulder harness and is connected with a strap that attaches between the occupant's helmet and said rod. Said strap is connected to the helmet via attachments in the helmet and a cable assembly, so as to allow the occupant's head to move freely from side to side. The strap elongates a controlled amount as the deceleration forces on the helmet, head and neck increase, thereby allowing for controlled restraint of the occupant's head and neck. The elongation rate of the strap might be tailored via the strap composition as to material, weave and density.